[FFmpeg-devel] [PATCH 1/2] avformat/aviobuf: Remove AVIOInternal and one level of indirection

[Andreas Rheinhardt]

Andreas Rheinhardt:
> On Mon, Jan 6, 2020 at 3:51 PM Andreas Rheinhardt <
> andreas.rheinhardt at gmail.com> wrote:
> 
>> In the Libav commit cae448cf, the opaque of every AVIOContext opened
>> by ffio_fdopen() (which is used internally by avio_open() and avio_open2())
>> changed: It was a simple pointer to an URLContext before, but now it was
>> a structure (namely AVIOInternal) containing a pointer to an URLContext
>> as its only member. The next commits (namely 8c0ceafb and ec4c4839) added
>> members to AVIOInternal to allow white-/blacklisting of protocols.
>>
>> But these two commits were never merged into FFmpeg (they were only
>> merged as no-ops in 510046c2 and 063b26d3), because FFmpeg chose
>> a different way to implement this (in 93629735); and so our AVIOInternal
>> still has exactly one member.
>>
>> This of course means that it is unnecessary to use AVIOInternal as
>> opaque as it is just adding a level of indirection (not only pointer
>> dereference, but also wrapper functions). Therefore this commit
>> removes AVIOInternal entirely and essentially reverts cae448cf.
>>
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>> ---
>>  libavformat/aviobuf.c | 86 ++++++++-----------------------------------
>>  1 file changed, 15 insertions(+), 71 deletions(-)
>>
>> diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
>> index 70e1d2ca10..0e2f038988 100644
>> --- a/libavformat/aviobuf.c
>> +++ b/libavformat/aviobuf.c
>> @@ -42,15 +42,10 @@
>>   */
>>  #define SHORT_SEEK_THRESHOLD 4096
>>
>> -typedef struct AVIOInternal {
>> -    URLContext *h;
>> -} AVIOInternal;
>> -
>>  static void *ff_avio_child_next(void *obj, void *prev)
>>  {
>>      AVIOContext *s = obj;
>> -    AVIOInternal *internal = s->opaque;
>> -    return prev ? NULL : internal->h;
>> +    return prev ? NULL : s->opaque;
>>  }
>>
>>  static const AVClass *ff_avio_child_class_next(const AVClass *prev)
>> @@ -940,49 +935,8 @@ uint64_t ffio_read_varlen(AVIOContext *bc){
>>      return val;
>>  }
>>
>> -static int io_read_packet(void *opaque, uint8_t *buf, int buf_size)
>> -{
>> -    AVIOInternal *internal = opaque;
>> -    return ffurl_read(internal->h, buf, buf_size);
>> -}
>> -
>> -static int io_write_packet(void *opaque, uint8_t *buf, int buf_size)
>> -{
>> -    AVIOInternal *internal = opaque;
>> -    return ffurl_write(internal->h, buf, buf_size);
>> -}
>> -
>> -static int64_t io_seek(void *opaque, int64_t offset, int whence)
>> -{
>> -    AVIOInternal *internal = opaque;
>> -    return ffurl_seek(internal->h, offset, whence);
>> -}
>> -
>> -static int io_short_seek(void *opaque)
>> -{
>> -    AVIOInternal *internal = opaque;
>> -    return ffurl_get_short_seek(internal->h);
>> -}
>> -
>> -static int io_read_pause(void *opaque, int pause)
>> -{
>> -    AVIOInternal *internal = opaque;
>> -    if (!internal->h->prot->url_read_pause)
>> -        return AVERROR(ENOSYS);
>> -    return internal->h->prot->url_read_pause(internal->h, pause);
>> -}
>> -
>> -static int64_t io_read_seek(void *opaque, int stream_index, int64_t
>> timestamp, int flags)
>> -{
>> -    AVIOInternal *internal = opaque;
>> -    if (!internal->h->prot->url_read_seek)
>> -        return AVERROR(ENOSYS);
>> -    return internal->h->prot->url_read_seek(internal->h, stream_index,
>> timestamp, flags);
>> -}
>> -
>>  int ffio_fdopen(AVIOContext **s, URLContext *h)
>>  {
>> -    AVIOInternal *internal = NULL;
>>      uint8_t *buffer = NULL;
>>      int buffer_size, max_packet_size;
>>
>> @@ -996,14 +950,10 @@ int ffio_fdopen(AVIOContext **s, URLContext *h)
>>      if (!buffer)
>>          return AVERROR(ENOMEM);
>>
>> -    internal = av_mallocz(sizeof(*internal));
>> -    if (!internal)
>> -        goto fail;
>> -
>> -    internal->h = h;
>> -
>> -    *s = avio_alloc_context(buffer, buffer_size, h->flags &
>> AVIO_FLAG_WRITE,
>> -                            internal, io_read_packet, io_write_packet,
>> io_seek);
>> +    *s = avio_alloc_context(buffer, buffer_size, h->flags &
>> AVIO_FLAG_WRITE, h,
>> +                            (int (*)(void *, uint8_t *, int))  ffurl_read,
>> +                            (int (*)(void *, uint8_t *, int))
>> ffurl_write,
>> +                            (int64_t (*)(void *, int64_t,
>> int))ffurl_seek);
>>      if (!*s)
>>          goto fail;
>>
>> @@ -1023,30 +973,28 @@ int ffio_fdopen(AVIOContext **s, URLContext *h)
>>      (*s)->max_packet_size = max_packet_size;
>>      (*s)->min_packet_size = h->min_packet_size;
>>      if(h->prot) {
>> -        (*s)->read_pause = io_read_pause;
>> -        (*s)->read_seek  = io_read_seek;
>> +        (*s)->read_pause = (int (*)(void *, int))h->prot->url_read_pause;
>> +        (*s)->read_seek  =
>> +            (int64_t (*)(void *, int, int64_t,
>> int))h->prot->url_read_seek;
>>
>>          if (h->prot->url_read_seek)
>>              (*s)->seekable |= AVIO_SEEKABLE_TIME;
>>      }
>> -    (*s)->short_seek_get = io_short_seek;
>> +    (*s)->short_seek_get = (int (*)(void *))ffurl_get_short_seek;
>>      (*s)->av_class = &ff_avio_class;
>>      return 0;
>>  fail:
>> -    av_freep(&internal);
>>      av_freep(&buffer);
>>      return AVERROR(ENOMEM);
>>  }
>>
>>  URLContext* ffio_geturlcontext(AVIOContext *s)
>>  {
>> -    AVIOInternal *internal;
>>      if (!s)
>>          return NULL;
>>
>> -    internal = s->opaque;
>> -    if (internal && s->read_packet == io_read_packet)
>> -        return internal->h;
>> +    if (s->opaque && s->read_packet == (int (*)(void *, uint8_t *,
>> int))ffurl_read)
>> +        return s->opaque;
>>      else
>>          return NULL;
>>  }
>> @@ -1216,17 +1164,15 @@ int avio_open2(AVIOContext **s, const char
>> *filename, int flags,
>>
>>  int avio_close(AVIOContext *s)
>>  {
>> -    AVIOInternal *internal;
>>      URLContext *h;
>>
>>      if (!s)
>>          return 0;
>>
>>      avio_flush(s);
>> -    internal = s->opaque;
>> -    h        = internal->h;
>> +    h         = s->opaque;
>> +    s->opaque = NULL;
>>
>> -    av_freep(&s->opaque);
>>      av_freep(&s->buffer);
>>      if (s->write_flag)
>>          av_log(s, AV_LOG_VERBOSE, "Statistics: %d seeks, %d writeouts\n",
>> s->seek_count, s->writeout_count);
>> @@ -1318,8 +1264,7 @@ int avio_read_to_bprint(AVIOContext *h, AVBPrint
>> *pb, size_t max_size)
>>  int avio_accept(AVIOContext *s, AVIOContext **c)
>>  {
>>      int ret;
>> -    AVIOInternal *internal = s->opaque;
>> -    URLContext *sc = internal->h;
>> +    URLContext *sc = s->opaque;
>>      URLContext *cc = NULL;
>>      ret = ffurl_accept(sc, &cc);
>>      if (ret < 0)
>> @@ -1329,8 +1274,7 @@ int avio_accept(AVIOContext *s, AVIOContext **c)
>>
>>  int avio_handshake(AVIOContext *c)
>>  {
>> -    AVIOInternal *internal = c->opaque;
>> -    URLContext *cc = internal->h;
>> +    URLContext *cc = c->opaque;
>>      return ffurl_handshake(cc);
>>  }
>>
>> --
>> 2.20.1
>>
>>
> Ping.
> 
> - Andreas
> 
Ping.

- Andreas